#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

class Calc
{
private:
   double m_nValue2;
   double m_nValue;

public:
   Calc(double nValue) { m_nValue = nValue; };

   double Add(double nValue) { m_nValue += nValue; return m_nValue;};
   double Subtract(double nValue) { m_nValue -= nValue; return m_nValue;};
   double Multiply(double nValue) { m_nValue *= nValue; return m_nValue;};
   double Divide(double nValue) { m_nValue /= nValue; return m_nValue;};
   double Modulus(double nValue) { m_nValue = fmod(m_nValue,nValue); return m_nValue;};
   double Power(double nValue) { m_nValue = pow(m_nValue,nValue); return m_nValue;};
   double Reciprocal() { m_nValue = 1/m_nValue; return m_nValue;};
   double NthRoot(double index, double guess, double pc)
   {
       double result = guess;
       double result_next;
       do
       {
           result_next = (1/index)*((index-1)*result+(m_nValue)/(pow(result,(index-1))));
           result = result_next;
           pc--;
       }while(pc>1);
       m_nValue = result;
       return m_nValue;
   };
   double Factorial()
   {
       double result = m_nValue;
       double result_next;
       double pc = m_nValue;
       do
       {
           result_next = result*(pc-1);
           result = result_next;
           pc--;
       }while(pc>2);
       m_nValue2 = m_nValue;
       m_nValue = result;
       return m_nValue;
   }
   double Factorial2(int nValue)
   {
       double result = nValue;
       double result_next;
       double pc = nValue;
       do
       {
           result_next = result*(pc-1);
           result = result_next;
           pc--;
       }while(pc>2);
       nValue = result;
       return nValue;
   }
   double DoubleFactorial()
   {
       double result=m_nValue;
       double result_next;
       double pc = m_nValue;
       do
       {
           result_next = result*(pc-2);
           result = result_next;
           pc--;
           pc--;
       }while(pc>2);
       m_nValue2 = m_nValue;
       m_nValue = result;
       return m_nValue;
   }
   double Gamma()
   {
       double result = Factorial()/m_nValue2;
       m_nValue = result;
       return m_nValue;
   }
   double Tetrate(double pc)
   {
       double result = m_nValue;
       double result_next;
       do
       {
            result_next = pow(result,m_nValue);
            result = result_next;
            pc--;
       }while(pc>1);
       m_nValue = result;
       return m_nValue;
   }
   double EvaluateBinomialCoefficient(double nValue)
   {
       double result;

       result = (Factorial2(m_nValue))/(Factorial2(nValue)*Factorial2((m_nValue - nValue)));
       m_nValue = result;
       return m_nValue;
   }
   double GetValue() { return m_nValue;};
   double SetValue(double nValue) { m_nValue = nValue;};
};

int main()
{
    double start;
    unsigned int operation;
    double operand;
    double operand2;
    double iterations;
    cout<<"What shall be your starting value?";
    cin>>start;
    Calc cCalc(start);

    do
    {
        cout<<"Select an operation, please.\n\n1. Addition\n2. Subtraction\n3. Multiplication\n4. Division\n5. Modulus\n6. Exponentiation\n7. Tetration\n8. Reciprocal\n9. Nth Root\n10. Factorial\n11. Double Factorial\n12. Gamma Function\n13. Evaluate Binomal Coefficient\n14. Set Value\n15. Show Value\n\n";
        cin>>operation;
        cin.ignore();

        cout<<setprecision(15);

        switch(operation)
        {
                         case 1:
                            cout<<"Select an addend, please.\n";
                            cin>>operand;
                            cin.ignore();
                              cCalc.Add(operand);
                              cout<<cCalc.GetValue()<<"\n";
                              break;
                         case 2:
                            cout<<"Select an minuend, please.\n";
                            cin>>operand;
                            cin.ignore();
                              cCalc.Subtract(operand);
                              cout<<cCalc.GetValue()<<"\n";
                              break;
                         case 3:
                            cout<<"Select an multiplicand, please.\n";
                            cin>>operand;
                            cin.ignore();
                              cCalc.Multiply(operand);
                              cout<<cCalc.GetValue()<<"\n";
                              break;
                         case 4:
                            cout<<"Select a divisor, please.\n";
                            cin>>operand;
                            cin.ignore();
                              cCalc.Divide(operand);
                              cout<<cCalc.GetValue()<<"\n";
                              break;
                        case 5:
                            cout<<"Select a divisor, please.\n";
                            cin>>operand;
                            cin.ignore();
                              cCalc.Modulus(operand);
                              cout<<cCalc.GetValue()<<"\n";
                              break;
                         case 6:
                            cout<<"Select a exponent, please.\n";
                            cin>>operand;
                            cin.ignore();
                            cCalc.Power(operand);
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 7:
                            cout<<"Select a number to tetrate to, please.\n";
                            cin>>operand;
                            cin.ignore();
                            cCalc.Tetrate(operand);
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 8:
                            cout<<"Select a number to take the reciprocal of, please.\n";
                            cin>>operand;
                            cin.ignore();
                            cCalc.Reciprocal();
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 9:
                            cout<<"Select an index, please.";
                            cin>>operand;
                            cin.ignore();
                            cout<<"Select a guess for the root, please.";
                            cin>>operand2;
                            cin.ignore();
                            cout<<"How many iterations of the algorithm?\n";
                            cin>>iterations;
                            cin.ignore();
                            cCalc.NthRoot(operand,operand2,iterations);
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 10:
                            cCalc.Factorial();
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 11:
                            cCalc.DoubleFactorial();
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 12:
                            cCalc.Gamma();
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 13:
                            cout<<"Choose an operand, please.";
                            cin>>operand;
                            cCalc.EvaluateBinomialCoefficient(operand);
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 14:
                            cout<<"Which number would you like to set the calculator to?\n";
                            cin>>operand;
                            cin.ignore();
                            cCalc.SetValue(operand);
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        case 15:
                            cout<<cCalc.GetValue()<<"\n";
                            break;
                        default:
                            cout<<"Sorry, but that isn't a feature yet.";
                            break;
        }
    }while(1==1);
}